Calling your partner “baby” or other pet names may be weird, but relationship counselors tend to think using pet names helps couples create a private world. In a frequently cited 1993 study published in the Journal of Social and Personal Relationships, Carol Bruess and Judy Pearson, researchers at Ohio State University in the US, found that happier couples tended to use more private language, a language that can only be understood by themselves. Bruess and Pearson interviewed 154 married couples — spanning every life stage, from newlyweds to empty-nesters — on how satisfied they felt with their relationship, and asked them to describe personal idioms they used with their partner. One-hundred-and-sixteen couples said they used at least one idiom; altogether, the couples reported a total of 370. Bruess and Pearson discovered that the more idioms a couple uses with each other, the stronger relationship they have.